Means and method for improving defenses against caries

ABSTRACT

Destruction of tooth tissues due to various microorganisms is slowed or prevented by introducing into the mouth arginine or an arginine precursor, especially peptides having from 2-4 amino acid units at least one of which is arginine.

RELATED APPLICATION

This is a division of application Ser. No. 868,933, filed Jan. 12, 1973,U.S. Pat. No. 4,154,813 and a continuation in-part of applicant'sApplication Ser. No. 697,538 filed June 18, 1976.

BACKGROUND OF THE INVENTION

The present invention is based on two well accepted observations. Cariesis more likely to occur when the pH of the mouth falls below a certaincritical level depending on the resistance of the individual and on theduration for which the critical level is exceeded. The secondobservation is the recognition that saliva itself has a salutary effecton the aforementioned caries causing factors which include some meansfor raising oral pH.

THE PRESENT INVENTION

It has been clear for some time that when an abundance of carbohydrates.particularly sugar, is present in the mouth, conditions favoring theproduction of an acid pH in plaque are sure to be present. The plaquemicroflora form acid from exogenous or endogenous carbohydrate. Thebalancing of this acid production has been observed to be my means ofproducing alkaline substances which neutralize the cariogenic acidsderived from the carbohydrates and return the pH of tooth surfaces to alevel above that at which caries will occur.

The present invention relates to providing a means to enhance thenatural defenses of the body against tooth caries when the latter are bycariogenic acids. It further is directed to replacing or supplementingthe natural protective function of saliva when it is diminished byatrophy of the salivary glands or other impairments which diminish thesecretion of saliva or the protective capability thereof.

It is an object of the present invention to provide a replacement orsupplement to the caries protective portion of saliva.

It is a further object to diminish or eliminate caries in otherwisesusceptible individuals by supplying suitable sources of pH adjustingcompound or precursors thereof.

Another object of the present invention is the utilization of arginineprecursors particularly peptides having 2-4 amino acid units, one ormore of which is arginine as the pH adjusting means.

It has been observed that plaque, the closely adhering spongy organicmaterial found on tooth surfaces accepts within its matrix molecules ofcertain size and shape. Peptides are among those compounds which canpenetrate plaque. It has been shown that these compounds penetratebacteria present in the mouth. It has been discovered that the materialwhich most readily counteracts the acid produced when an abundance ofcarbohydrate, particularly sugar, is present is arginine. Surprisingly,it has been determined that peptide of 2-4 amino acid units, one or moreof which is arginine, is effective in restoring mouth pH to anon-carious level.

It has been determined that generally, caries resulting from an acidicpH nearly invariably occurs when a pH of about 5 or 5.1 occurs for asufficient time while with only rare exceptions will caries occur if thepH is maintained at 6.1 or higher.

The question of duration of exposure of enamel to a pH lower than aboutpH 5 varies with individuals but certain generalities have beendetermined. Two schemes of activity may be posited. In the first, themouth is exposed to a limited amount of fermentable carbohydrate,usually sugar, after which the bacteria present in plaque convert thecarbohydrate to acids, mainly acetic, lactic and propionic. In this casethe pH drops as the above indicated acids are produced and a slowcountering production of alkaline amines occurs as susceptible peptidesor proteins give up amino acids which are decarboxylated by other oralbacteria. The two antagonistic reactions occur at rates such that the pHdrop which is achieved between about 5 and 15 minutes will usually reachthe pH level critical to the formation of caries unless the pH risefactor which has been found to be arginine and its precursors is presentand is acted upon by oral bacteria so that the pH fall is reduced andthe pH begins to return to the normal by the end of about 45 minutes to1 hour depending upon the particular mouth.

A second situation is represented by an availability of greater amountsof fermentable carbohydrate available for a longer time. The mouth pH inthis case goes below pH 5 which is conducive to the formation of cariesafter about 15 minutes and remains there while the excess of fermentablecarbohydrate is available. This can be for a period of 2 or more hours.It is under these conditions that a more serious carious attack occursbut in the presence of the pH rise factor the duration is reduced.

Experiments were performed in vitro using supernatant saliva. The salivawas obtained from random donors whose salivary secretions were paraffinblock stimulated. The saliva donations were pooled before and aftersediment removal.

A naturally occuring effective peptide in saliva has the arrangementH-glycine-glycine-lysine-arginine-OH with amino and carboxyl termini.This compound was synthesized by conventional methods and has proveneffective for the purposes of this invention and is a preferred pH risefactor. It being a compound which occurs naturally, it is a firstchoice, but the possibility of peptides having two or more arginineunits might prove even more effective.

The arginine containing peptide rapidly enters plaque and also entersbacteria itself. The peptide is stored there protected from dilutionproviding a potential source of alkaline material to counter-act acidformation activated by the presence of dietary carbohydrate. Thisstorage capability suggests inclusion of the peptide pH rise factor incommon dental products such as tooth pastes, tooth powders, mouthwashes,chewing gum and the like.

It has further been found that the oligomeric peptide pH rise factor iseffective even when provided to the mouth simultaneously withcarbohydrate substances which are operated upon by plaque bacteria toproduce acids. The addition of the pH rise factor to carbohydratecontaining substances such as sugared cereals, candy or chewing gum isan effective means for supplementing the natural defenses of the bodyagainst caries.

The arginine containing peptides are particularly suited as foodadditives in that many occur in nature, particularly the preferred oneof the present invention.

They are generally heat stable, tasteless, odorless and soluble inamounts beyond their effective level. They are esthetically acceptableas used.

The pH differences in the mouths of caries prone and caries freesubjects can be minimized by adding pH rise factor supplement to theformer. This is effective in proportion to the amounts of an argininecontaining peptide provided. A significant effect is produced with aslittle as 0.05 mM while as much as 3 mM and more continued to showimprovement.

Particularly interesting cooperation between the pH rise factor andfluoride ions has been observed. Fluoride ions in minor amounts such asabout 5 ppm reduces tooth solubility generally. It further inhibits thepH fall when the pH drops below about 5. The pH fall in the case of highsugar availability to 4.8 is held to 5.1 when 5 ppm of fluoride ispresent. This is about as high as fluoride ions alone can return the pH.When the pH rise factor of the present invention is also present,fluoride still inhibits the pH fall but the pH recovers earlier to safelevels of pH than when no factor is present.

The following are given by way of exemplification and not by way oflimitation.

Four sets of three 10×75 mm test tubes were provided with 0.2 ml of 8.4mM (millimolar) of aqueous glucose solution. Set I was provided with 0.2ml of pooled supernatant saliva. Set II was provided with 0.2 ml of 9.9mM of the peptide glycine-glycine-arginine. Set III was provided with0.2 ml of 9.9 mM arginine. Set IV was provided with 0.2 ml of distilledwater. Sequentially 0.2 ml of a 50:50 aqueous suspension of oralbacteria was added to each test tube. The concentration of the peptidein the combined composition was 3.3 mM. The prepared test tubes werekept at 37° C. in a water bath. pH readings were taken at 0 time whenthe bacteria was added and at 15, 30, 45, 60, 90, 120, 180 and 240minutes. The pH values are as follows:

    ______________________________________                                        TIME                                                                          (minutes)                                                                            0     15     39   45   60   90   120  180  240                         ______________________________________                                        Set I  7.4   6.2    5.9  6.1  6.3  6.4  6.5  6.6  6.6                         Set II 7.4   6.8    6.6  6.4  6.6  6.6  6.7  7.2  7.6                         Set III                                                                              7.3   5.8    5.4  5.2  4.9  5.0  5.0  5.3  5.8                         Set IV 7.3   5.8    5.2  4.9  4.7  4.6  4.3  4.5  4.5                         ______________________________________                                    

It is clear that supernatant saliva and an arginine providing supplementslows the pH fall in a carbohydrate rich environment. It is also evidentthat an arginine providing peptide is preferred to arginine alone. Insimilar experiments, an arginine providing peptide supplement acts tomoderate the pH drop more than either saliva alone or arginine alone andrestores the pH to its initial level or better.

The identification of the arginine providing peptide pH rise factorsuggests other areas wherein arginine containing peptides could beutilized. These compounds could be used in the regulation of manyprocesses involving microorganisms such as bacterial fermentations, winemaking, antibiotic production, citric acid formation and others.

Extensive testing of individual peptides of 2-4 amino acid units ascould reasonably be obtained or synthesized was done. The tests werecarried out under the same conditions as Sets I-IV. The salivarysediment was present in an amount of 16.7% (v/v), glucose 2.8 mM and thepeptide 3.3 mM in the final composition. Duplicate runs without peptidewere run parallel to the others as a double check. The pH starts atslightly above 7 and falls rapidly to between 4.5-5. An effective pHrise factor begins to reverse the fall within the first hour.Measurement continues through the fourth hour. The results were asfollows:

    ______________________________________                                        Arg-Leu      pH drop to 5.5, rising to about 7-8                              Lys-Leu      pH drop to 5.2 rising to about 5.5                               Pro-Pro      no significant pH rise                                           Pro-Pro-Pro  no significant pH rise                                           Pro-Ala      no significant pH rise                                           Meth-Pro     no significant pH rise                                           Arg-Ser      pH drop to about 5.5, rising to about 7.                         Lys-Ser      pH drop to about 5.3, rising to about                                         5.6                                                              His-Meth     pH drop to about 5.4, rising to about                                         5.5                                                              Asp-Arg      pH drop to about 5.4, rising to about                                         6.8                                                              Phe-Arg      pH drop to about 5, rising to 6.8-                                            7.8                                                              Gly-Arg      pH drop to about 5.2, rising to 7.5                              Arg-Gly      pH drop to about 5.5, rising to 7-7.9                            Arg-Lys      pH drop to about 6-6.7, rising to                                             7.2-8                                                            Gly-Gly-Pro  no significant pH rise                                           Gly-Gly-Gly  no significant pH rise                                           Gly-Gly-Arg  pH drop to 5.5, rising to 7.5                                    Gly-Gly-Lys-Arg                                                                            pH drop to 6.4, rising to 8.4                                    ______________________________________                                    

It is clear from the representative results that peptides of 2-4 aminoacid units one or more of which is arginine constitute providers of a pHrise factor. This is so whether the arginine moiety as linked to theother amino acids of the peptide by the carboxyl or amino group.

The invention has been described with respect to certain preferredembodiments but it will be understood that variations and modificationsmay be made therein without departing from the spirit of this inventionand the scope of the appended claims.

What is claimed is:
 1. A composition selected from the group consistingof a dental care product, a food product and a chewing gum whichcomprises a source of pH adjusting compound or precursor thereof having2-4 amino acid units of which at least one unit is arginine, in anamount effective to combat caries by controlling oral pH.
 2. Thecomposition of claim 1 wherein said amount is sufficient to release fromabout 0.05 to about 3 mM of said pH adjusting compound or precursor inthe oral cavity.
 3. The composition of claim 1 wherein the major portionthereof is a dental care product.
 4. The composition of claim 1 whereinthe major portion thereof is a food product.
 5. The composition of claim1 wherein the major portion thereof is a chewing gum.
 6. The compositionof claim 3 which contains an effective amount of fluoride ions.
 7. Thecomposition of claim 1 wherein said amino acid units have a sequenceselected from the group consisting of: Arg-Leu; Arg-Ser; Asp-Arg;Phe-Arg; Arg-Gly; Arg-Lys; Gly-Gly-Arg; and Gly-Gly-Lys-Arg.
 8. Thecomposition according to claim 1, wherein said amino acid units comprisea dipeptide of arginine and lysine, wherein said arginine moiety islinked to said lysine moiety by its carboxyl or amino group.
 9. Thecomposition of claim 1 wherein said amount is adequate to restore oralpH to a non-carious level.